We've done it twice, and it was easy! Both times, we got WAY more than any realtor wanted to ask for the house. I second the thing about the annoying realtor calls, though. I would stay away from the newspaper for just that reason (although my sister swears by the paper for her FSBOs...go figure!). We put "principals only" in our ad (as in, NO REALTORS), and it still didn't dissuade them from calling, coming to the house, peeking in the windows (no lie), leaving letters in our mailbox, etc. Our first FSBO sold by a sign on the street anyways, so that ad just created headaches for us in terms of dealing with persistent realtors who didn't understand the word "no".
The 2nd house that we sold FSBO was sold in an odd town where I knew that any buyer was going to be realtor represented. What I did was use an MLS listing service for $399 for a 6 month listing, and I put a 3% realtor commission in the listing. The ad was up on realtor.com w/in a day of hitting the MLS. I mentally upped my bottom-line price 3% for any buyer who came in with a realtor. That house did sell to a buyer with a realtor, and she was a pain. By the end of the transaction, her client had called me directly, and we worked everything out between us and the lawyer. Both transactions were handled by lawyers, even though the 2nd transaction was in a title company state.
Also, showings are much easier when you don't have somebody else scheduling them and telling you when you need to be out of your own house. I liked scheduling the showings myself. I never had a problem with a non pre-approved buyer, and neither did my sister who has sold FSBO 3 times. Every time, our lawyer gave them x number of days to get a mortgage approval, and every time that contingency was met with no issues. If it hadn't been, it would have been no biggie...we were taking backups right along on every FSBO, and we were up-front about that with our buyers.
BTW, I LOVED negotiating on my FSBOs. We didn't have to sell, so negotiating was really fun. Nobody cares more about getting you the best price for your house than YOU do!
Whatever you do, make sure that you have a good real estate lawyer involved. This goes even if you have a seller broker, because you really need a lawyer to protect your interests no matter what. Also, be sure to scrutinize the HUD-1 at least 48 hours prior to closing. We caught some errors on our last one due to poor preparation by the title company.